Astro Camera's - to cool or not to cool

[Outcast]

Gents,

I'm just curious about sensor cooling as a means of reducing noise in astrophotography.

I have a ZWO ASI224MC (uncooled) as well as an EOS1100d that I use; I'm only at the very beginning of my AP journey but, have noticed that my sensor on the ZWO is routinely up around 35 degrees... I live in the tropics where night time temperatures are often quite high.

I have seen a few you tube videos on adding a fan, heat sink & peltier cooling unit to the back. Some of the designs are pretty neat & very inexpensive & really only require very basic electronics understanding...

However, my biggest concern is the potential for condensation on the sensor... especially where I live where the dew point temp is quite high (tropics).., often around 23 degrees

I understand that the purpose built cooled cameras have a spot for putting in a desicant container to control condensation/dew that might form however, my camera & DSLR's probably won't accomodate such a thing...

I'm wondering if just using a heat sink & fan on the ZWO would do something to reduce sensor temp without bringing it down so far as to induce condensation.

Is there any value in this approach?

Then of course, there is the DSLR to tackle

Cheers

[xelasnave]

I am working up a design to house my Nikon d5500 with a 50 mm lens for some wide field with the Milky Way and LMC and SMC ...
I have thought about condensation ..I will put in some thing to take water out of the air and back off if that does not work☺ my idea us a flexible box made out of the insulation material I bought today.
I am not expecting much but on these hot nights it must help...but there are other areas that I can attend to like spacing capture 30 secinds apart...There may be an advantage there even if small...locating the camera battery away from the camera is what I am trying to sort now.
Alex

[xelasnave]

But to answer your question before some one who knows what they are talking about...go for it but consider the bagging approach simply because you should be able to control moisture that way..you make sure you can eliminate dew somehow.
Alex

[Ukastronomer]

google

https://www.youtube.com/watch?v=XSLIaLzFBW4&t=3s

[Outcast]

I'd be very interested to see what you come up with Alex.. I have a lot more research to do in this area & necessity is always the mother of invention...

Please share whatever design concepts you come up with, one for the benefit of all (which I know you are always generous about) & two, because you might get some useful critique & feedback taht enables you to improve upon your design.

Cheers

[Outcast]

Thanks Jeremy,

I think the other videos I've seen are by Martyn & offshoots from it... I don't think I had seen this one before but, no doubt useful to me as I look at options...

Cheers

Carlton

[kens]

Check out Jon Rista's web site. Scroll down to Dark Current Evaluation to see the effect of cooling.
https://jonrista.com/the-astrophotographers-guide/the-zwo-asi1600-guide/the-zwo-asi1600/preliminary-analysis/

[sil]

Yes to the first question, maybe to the second.

I added a heatsink (no fan, just heatsink) to my zwo 120mc and got a measurable 1C reduction in sensor temp.
Later I took apart a cheap garbage usb drink cooler which never cooled my drinks and stuck its peltier heatsink and fan to the zwo instead and was a reliable 13C reduction of sensor temp, cooler nights the outside of the zwo would be thick with white frost but I never had any sign it occured inside.

So technically YES you will get a temperature reduction with simple external heatsink setups. But if this results in a noticable improvement in images I can only assume maybe. Technically any cooling reduces noise, but noticably? Dont know, I only imaged planets or sun/moon so no long exposures where noise is most obvious. It was worth the exercise for me because I was curious but I can't say it resulted in better imaging but it should have a tiny bit and possibly prolonging the sensor life too.

But I can say I did once do a little longer exposure tests for fun and they were fairly noisy. Later I got the 174mc-cooled and that just blew the 120 away for noise and I think its worth every penny paying for the cooled version which give me a steady 32C below ambient and I dont think its worth trying to reach that delta with your own mods. Not a scientific comparison and very different sensors in those cameras but if you're a tinkerer and have a peltier already on hand then go for it.

[ChrisV]

There's a few on the EAA Forum at cloudy nights who have done this. Mainly for live imaging. One of the EAA gurus DonBoy did a nice fan/peltier on the 224 & 290 cameras

https://www.cloudynights.com/topic/584399-external-cooler-for-zwo-asi290-asi224-etc/

[Outcast]

Thanks Sil,

I might have a crack with the heatsink & fan only to start with & see how that goes.

The 224MC sensor is particularly good in respect to noise I have to say.. hopeful this may improve even more with some level of heat reduction...

Either way, it's a very inexpensive experiment so, nothing lost if it doesn't achieve much...

Cooled camera.. yeah, maybe one day...

I'm currently only doing short exposure stuff (Alt/Az mount) but, recently purchased a second hand EQ mount... initially to put my solar scope on.. maybe defork the meade at some point or, find a nice inexpensive APO.. LOL...

[Outcast]

Thanks Ken,

will check it out

[Outcast]

Cheers Chris

[xp1965]

Thanks , some useful info on the links

[glend]

Attempts to cool cameras that are not purposely designed for cooling attachment are almost certain to result in premature failure of the camera electronic, the reason internal condensation. Having built a few cooled DSLRs I know something about this topic. If you can seal the camera in a dry gas chamber or membrain you may have a chance.

[Outcast]

Hi Glen,

What about taking the approach of just a heatsink & fan?

Would this not drop the sensor a few degrees without producing condensation?

My issue is that sensor temp in FNQ is often up around 38 - 39 degrees. Adding a Peltier would likely result in condensation (our dew point can be up around 23 - 24 degrees) which as you correctly state would ultimately be disastrous for a camera not designed for cooling.

My thinking is that if a heatsink & fan could reduce temp by say 5 degrees, I might lose some heat related noise but, avoid condensation?

What are your thoughts on this approach?

Cheers

Carlton

[glend]

Yes, moving air over a heat sink will have some effect. A quality heat sink will be better than a cheap one, but you don't have a lot of room to work with on those uncooked cameras. A DSLR, like a Canon 450D, is actually a good choice because you can get a copper finger behind the sensor, so you can stop it from heating up beyond ambient.
But it is not a trivial mod to that camera, see rcheshire's thread on cooling in the archive here.
Good luck, i will be interested in what you come up with.

[iborg]

Probably won't work, but, an idea I have wondered about, get a box of dry ice, and feed the gas coming off it into the body of a camera.


I think the cold and dry gas should cool the camera, and with the gas flowing around the sensor, should keep ambient air, and its moisture, clear of the sensor - no condensation!


Possibly blow (or suck) air through the dry ice into the body (in-line fan) to get enough cooling.


Any moisture in the air will condense out before getting to the camera.


Philip

[glend]

Dry Ice is CO2, and CO2 will bond with and transfer moisture - ie it is not really a dry gas.

One idea I did try, was to use a PC processor liquid cooling system. I used it on one of my Canon 450D experiments. It's a bit involved, as you need a pump to push the coolant through a small radiator. The problem I had with it was the weight of the coolant in the tubes going to the camera copper cooling puck was creating a balance problem and it needed to be counter balanced.
It was a fun experiment though. You can buy all the PC liquid cooling parts from PC Case Gear online. I think I bought the camera cooling puck off eBay for a few dollars.

[JimsShed]

I made a cooler for my ZWO ASI185MC. Similar body to your 224's. Here in Brisbane over the summer the best delta I could achieve was about 15 degrees. So for me that translated from avg 34c sensor temp down to 15c. And after all that, my images were no better.
My camera was mounted in the eyepiece diagonal and everywhere that wasn't covered with the neoprene insulation was very cold to touch just like a cold can of beer. The problem with the DIY approach is the coldness doesn't get directly to the back of the sensor, and unfortunately I couldn't put a heat sink directly on the back of the sensor because there is a circuit board there. If you had a mill to machine some sort of enveloping heat sink around the perimeter of the sensor you might get a better result.
The other problem you will run into is the lack of cooling temp consistency from one night to the next, and even throughout the night; you would need to write some software to monitor the temp and regulate the cooler so you weren't constantly having to make new sets of darks for each temperature level. Sigh.

[JimsShed]

Forgot to mention. I also got full-on condensation on the filter I had put in front of the camera to protect the sensor.

[Outcast]

Thanks Jim,

Very useful to know.. as you probably know, our heat & humidity is even worse up here in Cairns.. that's why I was considering just heat sink & fan, to try & avoid that moisture problem...

It's gone off my list of priority projects at present but, next time I'm in Jaycar I might see what the bits will cost.. having said that though, if you got little improvement with a 15* drop in sensor temp.. I suspect chasing 5* will probably just be a waste of time.

Cheers

Carlton

[raymo]

Noise really starts to drop off below about 12-15, and freefalls once it gets
down into single figures. At about 4-6 noise was negligible with my 1100D.
raymo

[Outcast]

Cheers Raymo,

I suspect I will never get down to those temps up here.. best ambient low temp we get up here is about 14*, maybe a few nights of the year in the dry season.. if we are lucky...

I think the only way I will beat this in the end is with a dedicated, cooled Astro camera & to be honest, I don't think I can justify that expense.

I'll do my best to turn off any unnecessary in camera stuff, that will help to some degree but, probably not that much..

[Camelopardalis]

Carlton, you will get more thermal related noise with warmer ambient temperature, but the nature of it is somewhat random, so once you get going with your mount and all the software to control it, just enable dithering and it will help a lot with that. And then there’s always the old adage, just take more subs :D

Contrary to popular belief, you don’t always have to spend more money to enjoy the hobby and get good results ;)

[raymo]

The battery generates heat when powered up. Get a dummy battery for your 1100D on ebay, cheap as chips. It all helps. Once you begin stacking in earnest, stack large numbers of subs, that helps too. Sorry, Dunk just said that.
raymo

[xelasnave]

I have been thru the diy cooler but would say live without it and see how you can manage without via dithering and proceesing...and realise that one day you will probably want a dedicated cooled colour camera or horrors a narrow band set up...I was of the keep it simple approach until I decidedvto go narrow band...the difference was incredible and all I can say is if you keep at it you probably will end up narrow band...so be careful of wasting money in small fixes and just put money aside for narrow band one day...I wish I had not bought my nikon or 8 inch and just bit the bulet and got my 80mm and zwo narrow band set up first up...I would have saved $1k on the scope and $700 on the nikon...and each although handy are not as useful as the narrow band 80mm...I will set the 8 unch up but there is so much to do to make it really decent...the tube needs more structure as its like a tin can..more money and really needs a better focuser and its big...the 80 is less but the focuser is ok and its just so easy to manage compared to the 8 inch.
I cant see the 8 and the nikon being used as much as the 80mm.

I like you thought..oh its just too much money..but its not...tell me..how much do you need to spend to get a good bass and good amp?...mmm why not just get a cheap one☺
Alex

[sil]

For the desparate you can usuaaly easily unpin the battery cover on your dslr as most have some sort of spring clip holding the battery in the body anyway. This can allow the night air to help cool the battery as it heats up during use. Probably wont do squat for your imaging but should at least help battery life :)


Also before you experimenters waste a ton of money at jaycar on peltiers to play with, be advised they are expensive markups there. Instead jump on ebay and for under a fiver you can find chep crappy "usb drink coolers" that wont do squat for your drinks either but its a peltier, already wired to a usb connector and switch and often with heatsink and fan too all in some ugly chunk of plastic. Its a perfect buy to start experimenting with a peltier. Its what I installed on my zwo120mc and gives as good 13 deg delta. Cut out the lower power peltier and solder in a higher power one for more cooling..

Wonder if anyone's tried doubling peltiers, use a high delta one to suck heat out and sandwich a reversed lower delta on top to take the cold and realease heat on the outside straight to the air.. no interference from fans to worry about or bulky heatsinks? then build your pier with heat pipes to send heat into the ground? and pipe heat from all devices then into pier? :)

then there's the martian heat ray of course.

[Outcast]

Thankyou Gentlemen,

All good advice; I will investigate the dummy battery idea a little further.. a quick look on Ebay revealed they are indeed cheap as. The additional advice is appreciated from alcon.

Cheers